One app that requires root on the Samsung Galaxy A3 Duos is the DriveDroid app. With DriveDroid, you can give your Android a USB drive without actually using USB at all — or at least a great impersonation of one. It works by letting you drop a Linux ISO on your device, and you can then move that file over to USB to your computer.
- The following post is made for the Samsung Galaxy A3 Duos smartphone with the model number SM-A3000 only. Do not flash this file on one of the other variants or else you can soft-brick that device and get it stuck in a bootloop.
BEFORE WE BEGIN
- Download the Samsung USB Drivers  or the universal ADB Drivers from our USB Driver downloads page.
- Check you have the Developer Options already enabled on the smartphone by scrolling down the Settings menu. If you cannot see it there, that means you must unlock it before continuing. Do that now by heading to the Menu > Settings > About Device > Tap where it says the build number and keep tapping until it says you are now a developer. That means the Developer Options is now unlocked.
- Go back to the Settings menu, scroll down the list and tap where it says the Developer Options to enter the same on your device. Now look for the USB Debugging Mode and turn it on so it’s working.
HOW TO ROOT SAMSUNG GALAXY A3 DUOS ON ANDROID 5.0.2
- Download the updated version of the CF-Root tool by Chainfire for your A3000 smartphone from this link .
- Download the newest version of the Odin flashing tool from this link .
- Click and drag the two files from the default downloads location over to the desktop.
- Extract both files on the desktop of your computer by right-clicking and choosing the “extract here” option.
- Double-click the Odin executable file and run that Odin flashing tool on your computer.
- Reboot the Galaxy A3 in download mode by pressing the Volume Down + Home + Power buttons simultaneously after starting with the device off.
- Connect the Samsung Galaxy A3 device to the computer after you have installed the Samsung USB Drivers.
- Click the AP button from the Odin flashing tool user-interface.
- Upload the executable CF-Root file that is on the desktop.
- Click the Start button and wait for the Odin flashing tool to flash that rooting exploit by Chainfire on your A3 handset.
- You’ll get a pass message and that’s when you know your device is about to reboot.
- Now you can close Odin and unplug it from the computer.
- Open the Google Play Store and install the root checker application just to check that the device is rooted.
- Now you can open the Play Store again and start installing your rooted apps.
If you think the DriveDroid  app is one you might be interested in installing, you can grab it as your first rooted app. It comes in a free version and a paid version.